JPS6216335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cylindrical elastic bushing for coupling a suspension member to a vehicle body with a damping function.

2. Description of the Related Art In general, the body of an automobile is suspended by a suspension system, and the suspension member of the suspension system is connected to the vehicle body via a cylindrical elastic bush. For example, a semi-trailing arm suspension system is shown on page 98 of Service Bulletin (No. 401, November 1972) published by Nissan Motor Co., Ltd. In this suspension system, a pair of suspension arms that support wheels are attached to a suspension member so as to be able to swing up and down, and the suspension member extends in the left-right direction of the vehicle. The part is attached to the vehicle body via a mount insulator as a cylindrical elastic bush. The mount insulator includes an inner cylinder, an outer cylinder, and a main elastic body made of rubber that connects these inner and outer cylinders, with the outer cylinder facing the suspension member and the inner cylinder facing the inner cylinder. It is designed to be attached to the vehicle body via a mounting bolt that is inserted into the body. When the vehicle is running, vibrations from the power train system and vibrations received by the wheels from the road surface are transmitted to the suspension member via the suspension arm, and the vibrations of the suspension member are transferred to the buffering function of the main elastic body. Therefore, it is designed to suppress transmission to the vehicle body side.

However, the main elastic body of the mount insulator must not only perform a buffering function, but also function as a stopper for regulating displacement of the suspension member. For this reason, it is impossible for the main elastic body to simultaneously satisfy both the buffering function and the stopper function, which are contradictory to each other.
The problem was that vibrations in a certain vibration frequency band were inevitably transmitted to the vehicle body, and in particular, low-frequency vertical vibrations from the powertrain system were input, causing muffled noise in the room. For this purpose, it has been proposed to install a separate dynamic damper at the end of the suspension member. (Refer to Nitsusan Service Bulletin No. 419, June 1980) However, models equipped with a separate dynamic damper had the problem that they had many parts, increased costs, and were larger.

In view of these conventional problems, the present invention provides a cylindrical elastic bushing with a dynamic damper function, thereby allowing vibrations in frequency bands that could not be suppressed by the conventional cylindrical elastic bushings to be transferred from the suspension member side to the vehicle body side. It is an object of the present invention to provide a cylindrical elastic bushing which prevents the transmission of air to the surrounding area without increasing the size of the suspension and at low cost.

Means for Solving the Problems In order to achieve the above object, the present invention has an inner cylinder mounted on the vehicle body side, an outer cylinder mounted on the suspension member side, and a main elastic body connecting these inner and outer cylinders. In the cylindrical elastic bushing of the suspension member, the suspension member is supported by the vehicle body, and the outer cylinder is disposed at an end of the suspension member, and the outer cylinder is provided inside the outer cylinder in the vertical direction of the vehicle. It is constructed by mounting a mass body having a mass sufficient to perform a dynamic damper function via an auxiliary elastic body that undergoes shear deformation.

Effect With the above configuration, in the cylindrical elastic bush of the suspension member of the present invention, when vertical vibration is input from the suspension member to the outer cylinder, this vibration is transmitted to the mass body via the auxiliary elastic body. be done.
At this time, the phase of vibration is shifted by 180° between the mass body and the outer cylinder due to the auxiliary elastic body, thereby forming a dynamic damper. Furthermore, since the secondary elastic body is designed to be sheared in the vertical direction of the vehicle, which is the vibration direction of the power train system, the spring constant of the secondary elastic body can be adjusted in the vibration direction without increasing the size of the secondary elastic body. can be made smaller, and the resonant frequency of the dynamic damper can be tuned to the low-frequency vertical vibration frequency of the power train system, which is the cause of indoor muffled noise. Further, by providing the outer cylinder, that is, the cylindrical elastic bushing at the end of the suspension member, vibration reduction can be further improved.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 and 2 show a mount insulator 1 as a cylindrical elastic bushing showing an embodiment of the present invention.
The mount insulator 1 is used to connect a suspension member to the body of an automobile.

That is, the mount insulator 1 has an inner cylinder 2 and an outer cylinder 3 that are provided concentrically, and the inner and outer cylinders 2 and 3 are attached to a main elastic body 4 made of rubber which is fixed by vulcanization adhesive. connected by. The main elastic body 4 extends substantially in the left-right direction of the vehicle (left-right direction in FIG. 1).
Space portions 5 and 5a are formed between the outer cylinders 2 and 3 in the vehicle longitudinal direction (vertical direction in FIG. 1). Note that an intermediate plate 6 is provided within the main elastic body 4.

Here, in this embodiment, the space portions 5, 5
A pair of masses are arranged symmetrically with respect to the center of the axis of attachment to the vehicle body, that is, the center of the inner cylinder 2, via the auxiliary elastic bodies 7, 7a, on the opposing inner sides of the outer cylinder 3, using the space a. The bodies 8, 8a are fixed by vulcanization adhesive. The inner ends of the mass bodies 8, 8a are connected to the inner cylinder 2.
It is isolated from the main elastic body 4 and becomes a free end, and can vibrate freely without coming into contact with the main elastic body 4. Further, the auxiliary elastic bodies 7, 7a are adapted to be sheared and deformed in the vehicle vertical direction. The mass bodies 8 and 8a may be made of any material as long as they have a large mass (a size that allows them to function as a dynamic damper, which will be described later), but materials that have good adhesion to the secondary elastic body 7 are preferred. It is.

In the mount insulator 1 configured as described above, the outer cylinder 3 is attached to the suspension member 10 of a suspension system as shown in FIG. The suspension member 10 extends in the left-right direction of the vehicle, and the mount insulators 1 are mounted symmetrically at both end portions of the suspension member 10 with the vehicle centerline as an axis of symmetry. Furthermore, this third
The figure is a partial view showing one side of the suspension member 10, and 11 is an arm bracket to which a suspension arm on one side (not shown) is attached. Further, the inner cylinder 2 of the mount insulator 1 is attached to a vehicle body (not shown) via a bolt (not shown) inserted into the inner cylinder 2. Therefore, the suspension member 10 is coupled to the vehicle body via the mount insulator 1, and the main elastic body 4 of the mount insulator 1 bends and deforms the displacement of the suspension member 10 (displacement in the longitudinal direction of the vehicle). Alternatively, the suspension member 10 is compressed and deformed (displaced in the left-right direction of the vehicle), thereby suppressing vibrations from the road surface that are transmitted to the suspension member 10 from being transmitted to the vehicle body.

By the way, in the mount insulator 1 of this embodiment, the mass bodies 8, 8a are attached to the outer cylinder 3 via the auxiliary elastic bodies 7, 7a, so the vibration of the outer cylinder 3 is transmitted to the mass bodies 8, 8a. When this happens, the phase of the vibration in the specific frequency range shifts by 180 degrees and becomes the opposite phase, forming a dynamic damper. In other words,
When vibrations in a specific frequency range are transmitted to the outer cylinder 3, the mass bodies 8 and 8a vibrate with opposite phases, canceling out the vibrations of the outer cylinder 3 and causing the outer cylinder 3 to move from the inner cylinder 2. This can significantly reduce vibrations transmitted to the vehicle body. Therefore, by adjusting the mass of the mass bodies 8, 8a, etc., the vibration frequency range in which the dynamic damper effect is exerted is set to a frequency range that cannot be suppressed completely by the conventional main elastic body. Road surface vibrations transmitted from the device side to the vehicle body side can be significantly reduced. In addition, since the secondary elastic bodies 7 and 7a are designed to be sheared in the vertical direction of the vehicle, they are able to withstand vertical vibrations in the powertrain system that cause interior muffled noise.
The spring constants of the auxiliary elastic bodies 7, 7a can be made small, and the resonant frequency of the dynamic damper can be tuned to the low frequency vertical vibration frequency of the power train system, which causes muffled noise in the room. Therefore, vibrations in the power train system can be effectively reduced and muffled noise can be prevented.

By the way, in this embodiment, since the mount insulator 1 is attached to both ends of the suspension member 10, the suspension member 10
It is possible to effectively reduce the load input to the vehicle body due to the primary bending resonance that acts on the vehicle body.

Figures 4 and 5 show the suspension member of the mount insulator 1 when the mass of the mass bodies 8, 8a constituting the dynamic damper is changed, and when the mass bodies 8, 8a are kept constant (1 kg). Characteristic diagram A shows a comparison of vibration reduction effects using calculated values when changing the mounting position from both ends of 10.
Indicates B. That is, based on these characteristic diagrams A and B, the mount insulator 1 of this embodiment, that is, the mount insulator 1 with a built-in dynamic damper in which the mass bodies 8 and 8a are disposed within the spaces 5 and 5a, is suitable. However, it is clear that by attaching the suspension member 10 to both ends of the suspension member 10, wasted space can be used effectively and a sufficient effect can be exerted despite the small mass bodies 8, 8a.

In addition, when attempting to absorb vibration in the vibration direction (X direction in FIG. 2) of the suspension member 10 during the primary bending resonance, each dynamic damper is used to absorb vibration in the mount insulator 1 in addition to absorbing vibration in the vibration direction. The following two moments are given to That is, the moment due to the rotational movement of the mass bodies 8, 8a caused by the deviation between the centers of inertia of the mass bodies 8, 8a in the vibration direction and the elastic center of the mounting rubber, and the moment between the center of the mounting shaft of the suspension member 10 and the mass body 8. , 8a arises due to the deviation from the center of inertia. However, in this embodiment, by arranging the respective mass bodies 8 and 8a symmetrically with respect to the center of the mounting axis of the suspension member 10, the two moments are canceled out and vibrations can be effectively absorbed. becomes possible.

Furthermore, in the embodiment, each of the mass bodies 8,
Although the vibration absorption frequencies of the dynamic dampers 8a are shown as being the same, the vibration absorption frequency is not limited to this, and as long as the sum of the moments generated in each dynamic damper does not become too large,
The vibration absorption frequency of each dynamic damper can be made different, and by doing so, the vibration absorption effect can be exerted over a wider frequency range.

It goes without saying that the present invention is not limited to the commonly used semi-trailing type suspension member, but can also be applied to other suspensions, such as multi-link types.

Effects of the Invention As explained above, in the cylindrical elastic bushing of the suspension member of the present invention, the mass body is attached to the outer cylinder attached to the suspension member via the auxiliary elastic body. The elastic body and the mass body constitute a dynamic damper for the cylindrical body to which the mass body is attached, and can reduce vibrations in a specific frequency range transmitted to the cylindrical body. In particular, since the secondary elastic body is arranged so as to be sheared in the vertical direction of the vehicle, the resonant frequency of the dynamic damper against the vertical vibration of the powertrain system can be reduced, especially the low frequency of the powertrain system that causes indoor muffled noise. It is possible to tune the vertical vibration frequency, and it is possible to prevent and significantly reduce indoor muffled noise. Furthermore, since the elastic bushing is provided at the end of the suspension member, the vibration reduction effect can be further improved. Therefore,
By setting the frequency range in which this vibration is reduced to a vibration frequency range that cannot be suppressed by the main elastic body that connects the inner and outer cylinders and has a buffering function and a displacement regulating function, the basic vibration system can be reduced. This provides an excellent effect in that vibrations transmitted to the sides can be significantly reduced while satisfying the displacement regulation function.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a cylindrical elastic bushing showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line - 1 in FIG. Main part plan view showing the installation state, No. 4
This figure is a characteristic diagram showing the vibration reduction state with respect to the mass of the dynamic damper, and FIG. 5 is a characteristic diagram showing the vibration reduction state with respect to the mounting position of the cylindrical elastic bushing. 1...Mount insulator (cylindrical elastic bush), 2...Inner tube, 3...Outer tube, 4...Main elastic body, 7...Sub-elastic body, 8...Mass body, 10...Suspension Shion member.

Claims (1)

[Claims] 1. Consisting of an inner cylinder mounted on the vehicle body side, an outer cylinder mounted on the suspension member side, and a main elastic body connecting these inner and outer cylinders, the suspension member is supported by the vehicle body. In the cylindrical elastic bushing of the suspension member, the outer cylinder is disposed at the end of the suspension member, and a dynamic damper is installed inside the outer cylinder via an auxiliary elastic body that is sheared in the vertical direction of the vehicle. A cylindrical elastic bushing for a suspension member, characterized in that it is equipped with a mass body having a mass sufficient to perform its functions. 2. The cylindrical elastic bushing for a suspension member according to claim 1, wherein the mass body is arranged symmetrically with respect to the axial center of the inner cylinder.